Sports Nutrition From Science to Practice

Fat adaptation

why doesn't

it enhance

performance?

Should my

sports drink

be served

‘on the rocks’ ?

Do I WHEY

too much?

Should I eat a

low glycaemic index (GI)

pre-event meal?

Are carbohydrate

guidelines outdated?

Should I ‘train low’

and C2 Max

Hyponatremia

Can athletes really drink

too much water?

Cause of the female

athlete triad. Is

there a similar

problem in men?

Carbohydrate & Early Olympics

› 1896 Athens Games – Marathon

‘On the morning of the race, athletes were fed olives, eggs, cheese, milk & oranges with some consuming retsina wine’

‘Oranges were available during the marathon but athletes were unable to access water’

› 1904 St Louis Olympic Games

‘Water from a local well was used to supply competitors 12 miles into the marathon, however many suffered gastrointestinal distress as a

result’

‘ the marathon was won by Thomas Hicks who reportedly consumed a mixture of egg whites, 1/6th strychnine and brandy on the advice of

his trainers’

Carbohydrate Fuel Connection

Early 20th Century

› Fuel use misunderstood

› Early German pioneers (Von Leibig 1842)

‘muscular protein stores are the major fuel during exercise’

› Krogh & Lindhard 1920

- Compared low and high CHO diets

- Research was criticised

Early 20th Century

Harvard Medical school – Boston Marathon

› Blood from 20 runners (Levine 1924)

› Low BG associated with fatigue & stupor

› Following year supplemented with high CHO diet

› CHO during exercise, candy predominantly

› BG maintained, less fatigue & stupor (Gordon et al 1925)

› Confirmed Krogh & Lindhard - importance of CHO

Inaugural Victor from a field of 15 runners

John J McDermott of New York (1897)

Scandinavian Innovation 1960’s

0

10

20

30

40

50

60

70

80

90

0 20 40 60 80

Work Time (mins)

Mu

scle

gly

co

gen

(g

/kg

mu

scle

)

The breakdown of glycogen during intense cycling

Adapted from Bergstrőm et al 1967

0

50

100

150

200

250

300

0 10 20 30 40 50 60

Muscle Glycogen (g/kg muscle)

Wo

rk T

ime (

min

)

Muscle glycogen content, work time and

dietary carbohydrate intake

Adapted from Bergstrőm et al 1967

Low CHO

Mixed Diet

High CHO

Glycogen Loading -Innovation

0

50

100

150

200

250

0 1 2 3

Days

Mu

scle

Gly

co

gen

(m

mo

l

gly

co

so

l u

nit

s/k

g m

uscle

)

Glycogen content of the quadriceps femoris muscle from previously inactive

(Green) and previously active (Yellow) muscle of two subjects. Biopsies were

obtained immediately after one-legged exercise and during the subsequent 3

days of high dietary carbohydrate intake.

From Bergstrőm & Hultman 1966

0

50

100

150

200

250

0 1 2 3

D ays

J.B. E.H.

Are CHO Guidelines Outdated?

0

20

40

60

80

100

120

Tim

e t

o E

xh

au

sti

on

(m

in)

HCHO HFAT HFAT/CHO

Diet Condition

PRE

POST

Time to exhaustion in untrained men after a HCHO (65% of E) vs a HFAT (62% of E) after 7

weeks of endurance training 2-4 times a week. In 8th Week HFAT was switched to HCHO

Helge et al 1996

HFAT improved but

inferior to HCHO

Fat Adaptation Studies

Day 1 2 3 4 5 6 7

Diet HCHO

OR

HFAT

HCHO

OR

HFAT

HCHO

OR

HFAT

HCHO

OR

HFAT

HCHO

OR

HFAT

HCHO TT

Training

20 min @

70% VO2

Max + IT

3-4 hr

slow ride

Hill ride

2-3 hr

IT 3-4 hr

slow ride

20 min

@ 70%

VO2 Max

120 min

@ 70%

VO2 Max

+ 7 kJ

TT

Measures Biopsy

Blood &

RER

Biopsy,

Blood &

RER

Burke et al 2000

Compare Performance HCHO vs HFAT groups

Fat Adaptation

29.5

30

30.5

31

31.5

32

32.5

33

33.5

34

HCHO FADAPT

Tim

e t

o C

om

ple

te T

T (

min

)

Time to complete TT 7 kJ/kg at the end of 120 min of SS exercise on day 7 after

5 days of fat adaptation to high fat diet and 1 day of CHO restoration. P =0.21

Burke et al 2000

Improvement due to 2

subjects who performed

better on fat adapt but who

also had severe fatigue on

the HCHO

Subsequent study with sports

drink during exercise still no

performance benefit

Carey et al 2006

FAT-Adapt Reduces Glycolytic Capacity

Pyruvate dehydrogenase activity in the active form (PDHa) at rest and during 20

min of cycling at 70% VO2 peak followed by 1 min sprint at 150% of PPO on day

7 after either 5 days of FAT-adapt or HCHO Stellingwerff et al 2006

Reduced PDH

activity after only 5

days of FAT-adapt

Fat-Adapt

Glycogen

Sparing

BUT

Performance

Impairing

Train Low Compete High

Before the training period, maximal power output (Pmax) and time to exhaustion (Texh) at 90% of Pmax

were determined for each leg on separate occasions. Subjects (n=7), trained for 10 weeks consisting of

a 14 day cycle repeated 5 times. Workload was initially set to 75% of Pmax pre-training but was

increased 5-10% every 14 days depending on participant progress. Workload of each leg was equal

Blood &

Muscle

Biopsy

Blood &

Muscle

Biopsy

One leg trained 5 days a week – daily

One leg trained twice daily every other day – three days a week

Hansen et al 2005

1 2 3 4 5 6 7 8 9 10 11 12 13 14 Low ○ ○ ○ ○ ○

High ○ ○ ○ ○ ○

Week 5+6 Week 7+8 Week 9+10 Week 1+2 Week 3+4 Pmax Texh Pmax Texh

PRE-TRAINING TESTS POST-TRAINING TESTS TRAINING

Train Low, Compete High

0

5

10

15

20

Tim

e t

o E

xh

au

sti

on

(m

in)

Pre Post

Low

High

Low: Low leg trained with low glycogen protocol. High: high leg trained with

high glycogen protocol; a: P < 0.05 compared with pre-training, b: P < 0.05

between low and high Hansen et al 2005

a, b

a

Twice daily training

with 2nd session in

glycogen depleted

state = better

performance

Train Low in Well Trained

› 14 well trained cyclists/triathletes

› 18 lab cycling sessions over 3 weeks

› High (n=7) trained daily 6 day/week

- 100 min steady state ride (AT) one day

- High intensity interval training (HIIT) next day

- Rest day on day 7

› Low (n=7) trained every other day 3 days/week

- Same sessions but on the same day

- Train every second day

- AT in the am, 1-2 hr rest then HIIT (only water between)

Yeo et al 2008; JAP 105 (5); 1462-1470

Train Low in Well Trained

Yeo et al 2008; JAP 105 (5); 1462-1470

Low unable

to maintain

intensity

during HIIT

despite

financial

incentives

Train Low in Well Trained

Yeo et al 2008; JAP 105 (5); 1462-1470

Performance

improved

similarly in

LOW & HIGH

but LOW did

less HITT

Should Athletes Train Low ?

› Different ways to ‘train low’

- Low CHO diet

- Twice daily training

- Limiting CHO in recovery

- Prolonged training withholding CHO

- Train after overnight fast

› Why athletes want to train low

- Improve fat metabolism

- Decrease need for CHO in endurance events

- Reduce body fat (no evidence)

16

Risks of ‘Train Low’

› Unable to complete intense workouts

› Increase risk of illness (Gleeson et al 2004)

› Increased risk of injury (Brouns et al 1986)

› Overtraining symptoms (Peitbolis et al 2003)

› More studies are emerging

- Hulston et al 2010 (athletes); Morton et al 2009 (untrained);

De Brock et al 2008 (fasted); Akerstrom et al 2010 (fasted/fed)

- Performance improvement usually NOT in well trained

- All report ‘metabolic retooling’ (higher fat oxidation)

- Fuel timing – more research required (Burke; 2010)

17

Train low is

NOT for

children

Ramadan - Opportunity to Periodise Fuelling

› Safety Critical

- Modify time, duration & intensity

› Timing

- Sunrise sessions (muscle glycogen replete) – ‘high’

- Before Iftar (muscle glycogen deplete) –’low’

- 2-3 h after Iftar (hydrated; recovery possible)

- During fasting resistance training may reduce muscle loss

- Air-conditioned training during day (prevent dehydration)

› Cooling techniques

- Plunge pools and ice-vests (during the day training)

› Diet

› ‘Sahur’ meal support training goals for the day

› ‘Sahur’ foods a good sources of CHO (e.g. Dates) and protein (e.g. Milk)

18

Burke, 2011

Low GI Pre-Event Meals

Low Glycaemic Index Pre-Event Meals (Claims)

› Delay fatigue

› Prevent 30-60 min nadir in blood glucose levels

› Minimise insulin secretion

› Enhance fat oxidation

Science

› Mixed results from studies

› What benefit if use exogenous CHO during event?

› Should low GI be recommended?

19

CH

O d

uri

ng

Study name He

dge

s's

g

Lower Upper

limit limit p-V

alu

e

N Febbraio et al., 1996 0.915 -0.192 2.022 0.105

N Febbraio et al., 2000 -0.606 -1.556 0.344 0.211

N Sparks et al., 0.297 -0.636 1.229 0.533

N Chen et al., 2008a -0.662 -1.616 0.293 0.174

N Wong et al., 2008 -1.291 -2.320 -0.262 0.014

N -0.283 -1.009 0.443 0.445

Y Burke et al., 1998 0.184 -0.863 1.231 0.731

Y Chen et al., 2008b 0.370 -0.566 1.305 0.439

Y Wong et al., 2009 0.317 -0.569 1.203 0.483

Y 0.299 -0.249 0.847 0.286

Overall 0.087 -0.350 0.525 0.695

-4.00 -2.00 0.00 2.00 4.00

Favours HGI Favours LGI

Should Pre-Event Meals be low GI?

Sub-maximal Exercise + Time Trial

Inadequate support for

low GI pre-event meals

Carbohydrate During Exercise

Innovation

Evidence that carbohydrate feedings could

delay fatigue & improve ‘Gators’ performance.

Cade et al 1972

1975

American College of Sports Medicine First

position stand on fluid replacement

‘Water was better’

CHO < 2.5%

CHO Ingestion During Endurance – Improve Performance?

22

J Nutr 141: 890-897; 2011

ACSM Guidelines (1996; 2007)

• 30-60 g (up to 80 g per h)

• > 1 h

• 4-8% CHO

CHO Ingestion During Exercise – Improve endurance performance?

23

CHO Ingestion During Exercise – Does if improve performance?

24

Is 80 g of CHO/h the upper limit?

Glucose: Fructose (2: 1 ratios)

Should Athletes C2MAX?

25

MSSE: 40 (2); 275-81 (2008)

8% Performance

Improvement over

Glucose alone

Lean Machines

Dawn Frazer 100 mtr Freestyle

Olympian 1956, 1960, 1964

Shane Gould 1972

5 Olympic Medals

Freestyle & IM

Libby Trickett 2009 Olympian

Freestyle & Fly

Getty Images

Do Athletes ‘WHEY’ too much?

Moore et al Am J Clin Nutr 2009

Ceiling effect at 20 g

protein ~ 8 g EAA

Protein close to exercise is beneficial for hypertrophy in young men

Cribb & Hayes Med Sci Sports Exerc 2006

Better to be WHEY on Time

Protein around

the time of

training

improves gains

in lean mass

Timing of Protein Intake

Cribb & Hayes Med Sci Sports Exerc 2006

Timing right also

translated into

improved

strength gains

Is WHEY the Way?

Hartman et al Am J Clin Nutr 2007 Cribb & Hayes Int J Sports Nutr Exerc Metab 2006

Milk

20% whey; 80% casein Whey a soluble and ‘fast’ protein

Sports Drinks ‘On the Rocks’

Cooling

Vest Pre-Cooling Facial Cooling

Cool Showers

Beijing Olympics Acclimatisation

Impact of Heat on Exercise Fatigue

Central Nervous System

Motor

Drive Fatigue

Energy Metabolism

Cardiovascular Function

Fluid

Balance

Impact of Heat on Exercise Performance

33

Hot:

320C

Cool:

230C Hot:

400C

Cool:

200C

Exercise 70% VO2peak; P<0.05

Febbraio et al 1994

Beverage Temperature DOES it Matter ?

› When exercising in the heat cold (~4oC) beverages

compared to thermoneutral may…

- create a heat sink (consume enough)

- alter perception of thermal limits

- delay the rate of rise in Tc

- improve endurance performance

› Beverages ~10-20oC most palatable

- No research on ingested beverage temperature at events

Beverage Temperature - Cycle Port Macquarie Langkawi

Beverage Temperature - Run

Port Macquarie

Langkawi

Which Aid Station ‘Rocks’

vs.

Methods P

relim

inary

• VO2 max test

• Underwater weigh

Vis

its 2

-4

• Cycling 90 min (62% VO2max)

• 32°C, 40% RH

• 3.5 ml.kg Powerade TM every 15 min P

erf

orm

an

ce

• Self paced time trial (TT) (4kJ/kg)

• ICE: Ice slushy (-1°C);

• CON: Thermoneutral (37°C);

• WASH: CON + 25g slushy/ 5min and expectorate.

38

Performance

39

›Performance time:

- ICE: 18.3±1.4 min (p=0.03)

-WASH: 19.0±1.4 (p=0.32)

-CON: 19.8±1.2

›Mean difference: ICE vs. CON

-1.5 min (-2.75 to -0.25)

(8.2%, 1.3-13.9%)

210

220

230

240

250

260

270

280

290

Ave

rag

e P

ow

er

(W)

ICE CON WASH

p=0.02

Conclusion

›ICE beverage consumption

- Improved performance

-Reduced heat storage during steady state

- Increased heat storage capacity during performance test

-Reduced RPE and improved thermal comfort

-Reduced skin temperature

40

Ross et al 2011

Ice – Puree

1.3% improvement

performance time

BOSTON MARATHON

› 76 runners enrolled

› 488 (64%) finish line blood

› 13% hyponatremia (<135 mM)

› 0.6% critical hyponatremia (<120 mM)

› Associated with weight gain

- OR 4.2 ( 95% CI 2.2-8.2)

› Race time > 4 hr

› Small women

Almond et al 2005

Hyponatremia Simply Drinking Too Much water?

Hyponatremia

Noakes et al 2005

Relationship between serum [Na2+] and weight change at the end of racing in 2135

athletes

Athletes who

gain weight

most at risk

Hyponatremia

Three mechanisms explain hyponatremia

› Over-drinking - Behavioural or psychological factors

› Inappropriate ADH secretion - Failure to suppress ADH in face of in TBW

› Failure to mobilise sodium - Osmotically inactive sodium stores

- Inappropriate inactivation of circulating sodium stores

Mechanisms require

further investigation

Female Athlete Triad -ACSM 1997 Amenorrhoea

Osteopaenia

Low body

fat or weight

Inadequate energy

Inadequate protein, fat

& micronutrients

High fibre

Heavy training

Body Temperature

Hormone pulsatility Disordered

Eating

Low Energy Availability

Dietary intake (I) and exercise energy expenditure (E) were controlled to achieve

a balanced (B = 45 kcal/kg FFM/day) and deprived (D 10 kcal/kg FFM/day)

energy availability (A = I-E) treatments. D was achieved by diet restriction in

sedentary (S) women and by exercise in active (X) women

(a) Luteinising hormone (LH) pulse frequency in sedentary (S) and exercising (X)

women with the same energy availability. (b) Reduction in LH pulse frequency

caused by low energy availability in (S) and (X) women P < 0.01 Loucks et al 1998

Energy Deficiency

Periodise Physique “I need to eat

a lot less to

be lean”

Energy

for body

functions

Energy

Intake

Energy Burnt

Training

- = Regular

Menstrual Cycle

Does Energy Deficiency Impact Men?

Professional Jockeys

› Inadequate energy and nutrient intake

› Evidence of energy deficiency

› Low testosterone levels

› Reduced bone mass

Weight Making Sports

› Combating sports

› Rowing

47

IOC healthy Body Image U-Tube

48

Anezka Ruzucka

Gymnastics, Ukraine

Aiko & Tochi Nakata

Figure Skating Japan

Jessie-lee Nelson

Wrestling USA Akeyo Abasi

Athletics Kenya

http://www.olympic.org/hbi

Satisfying

your hunger

for GOLD

requires

satisfying

your body’s

need for fuel

Sports Nutrition From Science to Practice

Summary › Carbohydrate still CRITICAL to BEST performance for most athletes

- Fuel for the muscle but also the brain’

- Many athletes are ‘carbophobic’

- Periodising carbohydrate may be beneficial & work with Ramadan

- Right amount of carbohydrate not ‘high’-unlimited carbohydrate

- Carbohydrate during exercise beneficial (body & brain)

› Low GI pre-event meals not BETTER for endurance performance

› Protein around the time of training is WHEY GOOD

› You can drink TOO MUCH water during exercise

› Drinks during exercise in the heat should be COOL and often are not!

› Enough ENERGY is key to healthy HORMONES & BONES

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